Epidemiology seeks to improve public health by identifying risk factors for cancer and other diseases. Yet, the public does not always use that information to make appropriate health decisions. One reason might be that, even though a single risk factor can affect the risk of multiple diseases, this information is seldom communicated in a way that optimizes people's understanding of the importance of engaging in a single healthy behavior. Helping people understand how a single behavior could affect their risk of multiple diseases could foster a more coherent and meaningful picture of the behavior's importance in reducing health risks, increase motivation and intentions to engage in the behavior, and eventually improve public health. The objective of this study is to translate epidemiological data about five major health consequences of insufficient physical activity (i.e., colon cancer, breast cancer [women], heart disease, diabetes, and stroke) into a visual display that conveys individualized risk estimates in a way that is understandable and meaningful to diverse lay audiences. The aims are to 1) Identify which combination of four risk communication strategies most effectively conveys risk estimates of five diseases associated with physical inactivity, and 2) Incorporate these strategies into a visual display and compare its effectiveness to alphanumeric text. The study design, including identification and prioritization of primary and secondary outcomes, was guided by health behavior theory. The sample will be comprised of approximately 50% members of racial/ethnic minority groups and 50% with no more than a high school diploma. Participants will be enrolled from two sources: the GfK Knowledge Networks Internet Panel (N=1130) and a large Midwestern city (N=392). Participants in Aim 1 will be randomly assigned to one of eight experimental conditions in a 2x2x2 full factorial design. The conditions will vary according the whether the risk estimate is conveyed as a qualitative descriptor (e.g., high risk) vs. a numerical estimate, the presence/absence of social comparison information (i.e., how their risk compares to the average person), and the presence/absence of risk reduction information. Aim 2 will utilize a randomized controlled trial. Primary outcomes for both aims will be risk comprehension and intentions to increase physical activity. Secondary outcomes will be cognitive and affective perceived likelihood, response efficacy, perceived severity, and worry (Aims 1 and 2), and engagement in physical activity at 90-day follow-up (Aim 2). Potential moderators (i.e., race/ethnicity, education, numeracy) and mediators (e.g., response efficacy) will be examined for both aims. Completing the aims will impact public health by providing: 1) a versatile visual display that can be adapted to communicate multiple health risks in several domains, 2) a functional risk assessment tool that can be integrated into individual, community, or clinical interventions, and 3) increased basic and applied scientific knowledge. This research may also contribute to the reduction of health disparities; its focus on understanding demographic moderators will increase the applicability of the display to underrepresented groups.